The patriarch of the Simons clan is best known for his math chops and science philanthropy. But heirs Nat and Liz Simons are taking the family’s hedge fund fortune a different direction with some serious climate giving.

Around these parts, Jim Simons, who is worth $14 billion, is a staff-favorite science philanthropist due to his quirky personality, crazy life story, and his and wife Marilyn’s game-changing giving. But his kids Nat Simons and Liz Simons are really running with the family’s philanthropic legacy lately, albeit in a different direction. We’ve covered Nathaniel Simons' quiet climate change giving via his Sea Change Foundation, which is one of the nation's largest funders of climate and clean energy work. (It gave out $40 million in 2013.) But his sister Liz Simons is shaking things up in this realm too with a recent big announcement.

The headlines about a recent $48 million climate change commitment focused on some dude named Bloomberg, but the other partner in the initiative is none other than the Simons daughter, and husband and philanthropic partner Mark Heising.

Their joint clean energy initiative will make grants to state and federal nonprofits mostly, helping states transition their energy mixes to sources like wind and solar. In particular, it will help states meet emissions requirements mandated by the Obama administration. Likely recipients that have been named include the NRDC, and the Center for the New Energy Economy at Colorado State University.

This is the biggest and highest-profile climate giving we’ve seen from the California-based couple, but Simons and Heising have run the appropriately named Heising-Simons Foundation since 2007. One of four programs is the environment, and while it doesn’t hold a candle to Jim and Marilyn’s $2 billion-plus foundation, it got a sizable $234 million trust. In 2014, the funder made almost entirely six-figure grants for the environment, mostly going to clean energy and carbon reduction.

Some run-of-the-mill grantees include the NRDC and EDF, (EDF pulled in $3 million last year!) as well as the CSU clean energy center mentioned above. The foundation has also backed communications surrounding that “Risky Business” report that made an economic argument for fighting climate change.

This is all a bit similar to the pragmatic energy giving we've seen at her brother Nat Simons’ Sea Change, which gives big grants to key players and has put a lot of money into the communications side of the climate fight. But one thing we like about Heising-Simons is the refreshing amount of transparency. Sea Change is super-skittish, with maybe the least informative website we’ve seen. You gotta get into some tax forms to even find Nat in there.

Speaking of under-the-radar activity, one open question in all of this is how much the Simons are actually coordinating their giving. After all, there’s some serious blurring at the edges of these massive pots of money in the family. James and Marilyn have been donors to Heising-Simons, and the foundation is invested in Jim Simons’ hedge funds, Renaissance and Medallion. And there are some curious Bermuda-based funds feeding into the heirs’ foundations.

Regardless, we can't stress enough just how much money is waiting in the wings here. Even though he's retired, Jim Simons just keeps getting richer and richer, and he and Marilyn have signed the Giving Pledge. So as important as Nat and Liz are now, there's a good chance they'll one day be commanding billions of dollars in philanthropic assets. Pay attention to these people.